Field of the Invention
The present invention relates to handle designs for bags such as plastic trash bags. More specifically, the invention relates to forming integral ergonomically safe handles within a handle area defined at the bottom end of a bag.
Description of Related Art
Assignees of the present invention have designed ergonomic trash bags equipped with lower handles that help reduce workplace injuries. These bags are marketed as LiteLift® bags, and are described in U.S. Pat. No. 8,790,009 and U.S. patent application Ser. No. 13/601,924, the specifications of which are fully incorporated herein by reference. As described in these specifications, the ergonomic trash bag is constructed of plastic film. Typically, the bags are made from a continuous sheet of extruded tubular film that is run through machinery that forms the film into rolls of perforated bags. Generally, each bag has an open top for receiving items into a containment portion defined between layers of the film, a transverse bottom seal sealing together the layers of film at an end of the bag opposite the open top, a handle seal sealing together the layers of film to define a bottom end of the containment portion, and a handle body formed between the handle seal and the transverse bottom seal. The problem addressed in the present disclosure is how to form a graspable handle through the film of the handle body that is tear-resistant and that allows for realization through good manufacturing practice.
U.S. Pat. No. 6,231,232 to Charles J. Warr addresses a similar problem. In his disclosure, Warr teaches the formation of a hand-insertion slit formed in a handle area of the bag between two spaced-apart seal lines. The hand insertion slit is cut horizontally through the walls of the bag, with two arcuate end split portions formed on each end of the horizontal cut. Warr's invention includes forming the arcuate end split portions so that each defines an arc greater than or equal to 180 degrees, such that each arc also extends below the horizontal cut by an arc length of between 0 and 45 degrees. Essentially, Warr teaches angling the ends of the hand-insertion slit inward and away from the nearest perimeters of the bag to improve the strength, or tear-resistance, of the handle.
While Warr's approach seeks to improve the strength of the handle, it introduces new problems during manufacturing, particularly where the bags are formed from thin-film plastics. The first new problem is that the hand insertion slit, which is cut through all layers of the plastic film, creates a flap of plastic that can be hazardous as the film is being run through various stages in its forming apparatus. The flap tends to fold over and get caught in various components of machinery, causing tears and jamming. The second problem occurs when the arcuate end portions of Warr's hand-insertion slit are formed as cut-outs. The circular portions of film that are removed to form the cut-outs tend to disperse and jam the bag-making machinery, and also create debris that requires additional resources to remediate.
What is needed is a new design for bag handles that is tear-resistant, that reduces defects, and that enables better manufacturing reliability.